专业英语教学6.docVIP

UNIT6 EXHAUST SYSTEM The exhaust system carries exhaust gases from the engine’s combustion chamber to the atmosphere and reduces, or muffles, engine noise. Exhaust gases leave the engine in a pipe, traveling through a catalytic converter and a muffler before exiting through the tailpipe. 排气系统将废气从发动机燃烧室排到大气中并降低或消除发动机噪音。废气经排气管排出发动机后，要先穿过催化转换器和消声器，然后从排气尾管排出。 6.1 The Tailpipe （排气）尾管 The tailpipe is a long metal tube attached to the muffler. It sticks out from under the body of a car, at the rear, in order to discharge the exhaust gases from the muffler of the engine into the air outside the car. （排气）尾管是一个连接到消声器的长金属管。为了将废气从发动机消声器排出到汽车外的大气中，尾管从汽车车身尾部下方伸出。 Stick out　突出，伸出 6.2 The Muffler　消声器 背景：发动机的排气压力为0.3～0.5MPa，温度在500～700，这表明排气有一定的能量。同时，由于排气的间歇性，在排气管内引起排气压力的脉动。若将发动机排气直接排放到大气中，将产生强烈的、频谱比较复杂的噪声，其频率从几十赫到一万赫以上。排气消声器的功用是降低排气噪声。消声器通过逐渐降低排气压力和衰减排气压力的脉动，使排气能量耗散殆尽。Exhaust gases leave the engine under extremely high pressure. If these gases escaped directly from the engine, the noise would be tremendous. For this reason, the exhaust manifold sends the gases to a muffler where they go through metal plates, or tubes, with a series of holes. The pressure of the gases is reduced when they pass through the muffler, so they go out of the tailpipe quietly. 废气是在高压下被排出发动机。如果这些废气直接排出发动机，噪声会非常大。因此，排气歧管要先将废气送到消声器中，在那里废气要穿过带有许多小孔的金属板或金属管。当废气通过消声器时，压力会被减弱，这样在它们被排出尾管时就会非常安静（声音就会很小）。 The muffler is made of metal and is located underneath the body of a car. It’s connected between the tailpipe and the catalytic converter. 消声器由金属制成，位于车身下方，连接尾管和催化转换器。 There are two types of muffler design. One type uses several baffled chambers to reduce noise. The other type sends the gases straight through perforated pipe wrapped in metal or fiberglass. This type of muffler is designed for the purpose of reducing backpressure and, consequently, makes slightly more noise. 消声器有两种设计类型。一种采用带有几个隔板室（消声室）来降低噪声，另一种是将废气直接送入用金属或玻璃纤维包装的多孔管。这种类型的消声器设计目的是减小反压力（背压），从而产生更多的轻微噪声。 wrapped in用…包装，缠绕，覆盖 The muffler quiets th